Yarn manufacturing textile machines comprise at least one row of identical workstations arranged next to each other on which yarn is wound on bobbins. For a variety of reasons, such as increasing the speed of spinning and the speed of winding yarn, reducing human labour, improving the quality and uniformity of the attending operations at the workstations, etc., yarn manufacturing textile machines are equipped with at least one attending device that is movable along the row of workstations and is provided with working means for performing required operations, or at least part of the operations, at the individual workstations. There are other types of yarn making textile machines that include workstations, each of which is provided with its own handling means performing partially or completely the attending operations or participate in the attending operations in cooperation with an attending device.
During the activities of the attending device on a yarn manufacturing textile machine, for example, during the resumption of the spinning process at the workstations after previous termination of production at part of the workstations or at all the workstations, or after the doffing of a wound bobbin and exchanging it for an empty tube, or after a yarn break at the workstation, etc., it is necessary not only to control the movement of the attending device along the row of workstations, but also to control the individual attending activities performed at the workstations.
Methods for controlling the movement and operation of an attending device for attending the workstations of a yarn manufacturing textile machine are known which use various information about the course of production at the individual workstations and about the previous activities of the attending devices on the machine and at the individual workstations. However, these methods of control work mostly with a pre-set fixed algorithm, which can be altered externally to the machine by the machine operator but which cannot be changed during the operation of the attending device. In the event of a failure of an attending operation carried out by the attending device, the attending device makes a new attempt to perform successfully the attending operation, whereby the maximum number of attempts to carry out the attending operation is pre-set in the control system. If the last attempt to perform an attending operation from a set number of attempts does not lead to a successful operation at the given workstation, the workstation is evaluated by the control unit as a workstation with a fault and the machine operator is informed about this.
According to another known method of control, the attending device moves according to the information from the control unit along the row of workstations from one workstation being operated to another in such a manner that it moves to the closest workstation requesting an attending operation and carries out the attending operation either independently or in cooperation with the handling means of the workstation. This procedure, which is pre-programmed, is repeated. The attending device usually moves to the workstations in which the production process is to be resumed by operating the workstations one by one in the sequence in which they have been stopped but with regard to the operation of any other attending device present on the same machine.
EP 394 671 discloses a method for controlling an attending device moves along a row of workstations from one end of a yarn manufacturing textile machine to the other end and back again and then repeats this procedure. In doing so, it stops in succession (one at a time) at the workstations at which attending activities have to be performed if it is possible. At the workstations where the need for an attending operation has occurred only after the mobile attending device has passed past these workstations, the attending operation is performed only after the attending device has passed these workstations again when moving in the opposite direction.
DE 19 917 971 describes a method for controlling an attending device that is provided with a control unit communicating with the control unit of the machine, wherein the attending device moves along a row of workstations of a yarn manufacturing textile machine and stops in succession at the workstations (at one at a time) where it performs an attending operation until it is successfully completed by one or even more (e.g. 2) pre-determined attempts. Only when the pre-determined maximum number of unsuccessful attempts has been exceeded, the attending operation is interrupted and the workstation which has not been set into operation is marked and stored in memory. The attending device then moves and operates the next closest workstation requesting an attending operation. A new maximum number (e.g. 3) of attempts to perform the attending operation can be set before the next passage of the attending device past the unsuccessfully spun-in workstation, which the attending device can carry out during a new passage. Only when this new limit of the number of attempts is exceeded, the workstation of the textile machine is assessed by the control unit as incapable of operation, whereby the unsuccessful attempts of attending activities are classified and counted according to the type of failure.
EP 3 115 487 discloses a method for controlling an attending device of a yarn manufacturing textile machine provided with a control unit or connection to a control unit, in which the attending device moves along a row of workstations equipped with yarn sensors monitoring the parameters and presence of the produced yarn. The workstations can have their own complete or partial handling means for resuming the manufacturing process which cooperate with the attending device in performing the attending operations. Each workstation is continuously evaluated according to one or more production-related parameters and on the basis of this evaluation, the sequence of the workstations to be serviced or to be spun in for the resumption of the production is determined with the aim of achieving the maximum production efficiency of the entire machine. The parameters evaluated include, for example, the reliability of the workstation operation, the time needed to renew production and the number of attempts for successful resumption of the production, the production efficiency of the workstation, the amount or the length of the yarn produced per time unit, the operating time of selected components, etc. All these parameters are used as input parameters for the mathematical model of the machine operation which is created for this purpose, whereby the procedure of the control operations to resume production is approved prior to commencing attending activities at the workstation.
If these parameters are considered upon the selection of the next workstation where the production will be resumed, the total time that is required for the resumption of the manufacturing process of the workstation of the yarn manufacturing textile machine per hour of operation can be minimized, and/or the overall production efficiency of the yarn manufacturing textile machine can be increased.